docs: def point_dist2(p1, p2):
      '''compute the square of the euclidian distance between two 3D points
  
      Args:
          p1, p2: indexable objects with
          indices 0, 1, 2 corresponding to 3D cartesian coordinates.
      Returns:
          The square of the euclidian distance between the points.
      '''
      v = vector(p1, p2)
      return np.dot(v, v)